38 C.F.R. § 20.300
(b) Waiver of appellant's right to submit evidence. For appeals described in 20.302 and 20.303, an appellant has a right to submit evidence during a period of 90 days, unless this right is waived by the appellant or representative at any time prior to the expiration of the applicable 90-day period. Such a waiver must be in writing or, if a hearing on appeal is conducted pursuant to 20.302, the waiver must be formally and clearly entered on the record orally at the time of the hearing.
(Authority: 38 U.S.C. 7104)
[84 FR 182, Jan. 18, 2019]